The activity of single lateral line afferent neurons was chronically recorded in free-swimming toadfish. CNS efferent neurons, known to be inhibitory upon peripheral lateral line mechanoreceptors, were activated by stroboscopic and natural visual stimuli. Discharges from irregular-type afferents caused by water movement relative to lateral line neuromasts decreased following stroboscopic stimulation of unrestrained and behaving fish. Visual presentation of natural prey also decreased mechanically evoked afferent firing rates. We show that visual stimuli can activate the efferent system and function in the peripheral processing of mechanical stimuli to the lateral line in biologically relevant contexts.